splicing power adapter to different connector

[nickBcap]

Hi, someone gave me a small laptop to repair and the power adapter failed. I have an adapter I was not using and clipped the connector of the failed adapter and clipped the connector off the good power adapter to splice the good power adapter to the correct connector but see now(lol not really) that the insides of the cables are not identical and my inexperience has now been revealed - which wire should connect to which?
The photo shows the 2 different adapters and the insides of the two cables.
I hope you can see the image hosted in Microsoft One Drive.
I have now guessed the White Wire which is the centre wire in the Compaq adapter cable may be the +ve wire because the Centre Pin in the Compaq Connector is +ve and the Centre and Outer wires are written on the Compaq Power Adapter label, and the Red Wire may be the +ve on the Compatibile power adapter, but just want to be sure.
Here is the link cut up because the IMG link appears to be not working...(one space) htt p://1drv.ms/1yzk2CA

[stj]

Re: splicing power adapter to different connector

dont use hosts,
upload the foto direct.

[mariushm]

Re: splicing power adapter to different connector

Sigh... see this logo on both adapters?



This tells you that the external surface of the jack is NEGATIVE and the internal pin is POSITIVE.

Connect the wires to the plug in whatever way you want. Plug the adapter in the mains, grab a multimeter, put it on voltage and put black probe outside the connector and touch the inside pin with the red probe.
If you have +18..+20v you got the wires right. If you see a negative voltage, you got the wires wrong, so flip them around.

note.
The common/standard convention is too insulate the positive and use those unshielded wires for negative. If both wires are insulated, it's usually black for negative, red for positive (hot)
Still, it never hurts to double check with a multimeter.

[nickBcap]

Re: splicing power adapter to different connector

Yes, the logic of the centre white wire to be fixed to the centre pin took my fancy already and I went ahead and soldered the wires and soldered black to the shielding outer wires but have not tested the adapter yet. I was preparing to just "do it" but will now test the power adapter on with my multimeter.
Thanks for the advice and I don't think I know how to just post a picture directly into the post but below is an attempt, but if it appears ...
If a guy can access the picture and see what I am trying to show the forum then I have to begin to wonder so please don't mind the laugh.

[stj]

Re: splicing power adapter to different connector

ffirst, you dont use the quick reply box,
you click "post reply"

type your text,
scroll down to "manage attachements"
then select the file with the "choose" button,
then click "upload"

then click "submit reply"